1. Field of the Invention
The present invention relates to communication networks and, more particularly, to a method and apparatus for transporting Ethernet services, where the Ethernet service itself might be used to carry other native services.
2. Description of the Related Art
Data communication networks may include various computers, servers, nodes, routers, switches, bridges, hubs, proxies, and other network devices coupled together and configured to pass data to one another. These devices will be referred to herein as “network elements.” Data is communicated through the data communication network by passing protocol data units, such as frames, packets, cells, or segments, between the network elements by utilizing one or more communication links A particular protocol data unit may be handled by multiple network elements and cross multiple communication links as it travels between its source and its destination over the network.
The various network elements on the communication network communicate with each other using predefined sets of rules, referred to herein as protocols. Different protocols are used to govern different aspects of the communication, such as how signals should be formed for transmission between network elements, various aspects of what the protocol data units should look like, how packets should be handled or routed through the network by the network elements, and how information associated with routing information should be exchanged between the network elements.
Large communication networks generally include subscriber networks, provider-based access networks, and core networks. Subscriber networks are commonly referred to as Local Area Networks (LANs), such as may be implemented by a corporation or university, or even in a residence. Access networks are used to aggregate traffic from a large number of subscribers, and generally encompass an area such as a metropolitan area or regional geographic area. Core networks are generally used to transport data between access networks. Access and core networks may exist in many different geographic areas and may be connected in myriad different ways.
Traditionally, Local Area Networks (LANs) have implemented a network protocol such as Ethernet to enable network elements on the LAN communicate with each other. Ethernet is a well known networking protocol that has been defined by the Institute of Electrical and Electronics Engineers (IEEE) 802 Groups. Conventionally, Ethernet has been used to implement networks in enterprises such as businesses and campuses, and other technologies have been used to transport network traffic in the access and core networks. Specifically, network providers such as carriers that sell bandwidth to subscribers on the access and core networks were reluctant to deploy networks based on Ethernet technology, since Ethernet was designed to provide best efforts service and did not support various control and management functions that were deemed necessary by network providers. As the Ethernet specifications have evolved, however, and as advancements have been made to Ethernet technology, some of these issues are being resolved. Consequently, many service providers are starting to use Ethernet to implement portions of their networks.
It is not uncommon for networks to be connected to enable packets to flow from a subscriber's LAN over access and core networks (which may be provided by a service provider or another entity), and then back onto a different portion of the subscriber's LAN. To enable this to happen, the particular manner in which the packet is handled may make a large difference as to the amount of coordination required between the various networks.
Networks may be viewed as having three layers—a data layer, a control layer, and a management layer. The data layer is related to how data is actually transmitted on the network. The control layer is related to how the network elements on the network interoperate. The management layer is related to how operation of the network may be monitored so that faults may be detected and corrected in a timely manner.
Depending on who owns which portions of the network, it may be desirable for one or more of the network areas to have shared control or management planes. For example, a network provider may own access networks in multiple cities and may want them to be commonly managed and to share control information. Depending on the particular way in which the networks are connected, it may be necessary for the networks to work together so that control and data may be passed between the networks. This type of interworking may require significant coordination and may be difficult to implement in situations where one service provider does not own all sections of the network.